Since before the turn of the century, the use of a spinning frame or twister in the manufacture of textile yarn, both cotton and manmade, has been widespread. A vital part of the spinning frame is known as the spindle which consists of a steel blade and bolster. A quill or bobbin has been an essential companion to the spindle since the invention of the spinning wheel, and the method of mounting the quill on the spindle has always presented a problem.
Prior to the advent of top-drive filling spindles, an acorn type or "bottom-drive" filling spindle was widely used. In this case, the quill, normally made of wood or the like, was applied to the revolving spindle to wind the textile yarn onto the quill after twist has been imparted thereto by the spinning frame, spinning ring and traveler. With the use of the acorn type of spindles, the speeds attainable therewith were somewhat limited due to gyration of the quill on the spindle. These gyrations further caused inconsistencies and imperfections to appear in the woven fabrics.
Accordingly, those skilled in the art turned to top-drive filling spindles with increasing frequency. In designing the spindle, provisions were made for this spindle to carry its full load without vibration or gyration. With the use of top-drive filling spindles, the drive point between the spindle and quill was moved from directly above the acron of the spindle to the tapered tip of the spindle. The tip is tapered at the top to fit the internal bore of the quill, the contact between the spindle and quill at this point providing the sole driving of the quill. By utilizing this mode of driving the quill, it tends to find its own center of rotation, the gyration or vibration is greatly reduced, and, as a result, much higher spindle speeds are possible to achieve and are actually accomplished.
Although the spindle is of induction hardened steel, wear still occurs on the spindle tapered tip after three or four years. Thus, slippage between the spindle and quill occurs, thereby causing less than calculated twist in the yarn being spun. It therefore becomes necessary to rework the taper of the spindle, so as to restore the original dimensions to the tapered spindle tip and consequently obtain additional use therefrom. In the past, this reworking has consisted of two basic methods: (a) a rehardening of the spindle tip and subsequent regrinding of the taper; and, (b) cutting the old tip off and subsequently butt welding a new tip on, rehardening, and then grinding to the desired taper. Both of these methods have advantages and disadvantages. In the simple rehardening process (a), the obvious advantage is cost and, normally, less manufacturing time, while the big disadvantage is that the regrinding process removes metal from the spindle tip, thereby causing the quill to drop and give less clearance at the acorn (bottom) of the spindle. This clearance is, of course, critical and if the grinding is not carried out with extreme accuracy, the result will be an acorn driven quill that results in much gyration and vibration. The advantage of the butt welding method (b) is that the disadvantage of the rehardening process is eliminated, as a new spindle specification is restored. However, the disadvantage of this method is cost, usually more manufacturing time and a relatively high percentage of butt weld failures. Additional disadvantages of both methods is the normal use therein of induction type hardening of the tips. Induction hardening of steel results in layers of hardening, with each successive layer from the outer case or surface producing a lower degree of hardness. In the actual use of a spindle tip hardened by these methods therefore, wear is greatly accelerated once the outer hardness becomes worn away. As a result, spindle tips produced thereby have a relatively short useful life span.
Another object of the present invention is to provide an economic, efficient and reliable method of retipping worn top-drive filling spindles.
Still another object of the instant invention is to provide a top-drive filling spindle having a tapered tip portion that can be successfully retipped an indefinite number of times with ease, speed and low cost.